import math
x1,y1,x2,y2 = (float(x) for x in input().split())

d =  math.sqrt((x2 - x1)**2 + (y2 - y1)**2.0)
print (d) import math math float(x) for x in input().split() for x in input().split() x input().split() ().split () input split for x in input().split() float(x) float x x1,y1,x2,y2 = (float(x) for x in input().split()) x1 (float(x) for x in input().split()) y1 x2 y2 d =  math.sqrt((x2 - x1)**2 + (y2 - y1)**2.0) d math.sqrt((x2 - x1)**2 + (y2 - y1)**2.0) math.sqrt math sqrt (x2 - x1)**2 + (y2 - y1)**2.0 (x2 - x1)**2 x2 - x1 x2 x1 2 (y2 - y1)**2.0 y2 - y1 y2 y1 2.0 print (d) print d x1,y1,x2,y2 = (float(x) for x in input().split()) (float(x) for x in input().split()) x1 d =  math.sqrt((x2 - x1)**2 + (y2 - y1)**2.0) math.sqrt((x2 - x1)**2 + (y2 - y1)**2.0) d y1,x2,y2 = (float(x) for x in input().split()) (float(x) for x in input().split()) y1 x2,y2 = (float(x) for x in input().split()) (float(x) for x in input().split()) x2 y2 = (float(x) for x in input().split()) (float(x) for x in input().split()) y2
import math
x1,y1,x2,y2 = (float(x) for x in input().split())

d =  math.sqrt((x2 - x1)**2 + (y2 - y1)**2.0)
print (d)
